his name is dzhokhar tsarnaev. he is 19 years old believed to be chechen, has been i t unitteeds for about 12 years since the age of 7. he is believed to be armed and dangerous described as a terrorist as the boston chief of police and have the entire city on lockdown. the stores and schools are closed. mass transit is closed. police are outside the home of tsarnaev there in cambridge, massachusetts, on norfolk street and believe it's possible there are more explosives on the scene. it's even -- they're looking at the possibility of more accomplices, as well and want to go to abc's chief investigative correspondent brian ross for more on that. brian. >> reporter: well, george, they've imposed a no-fly zone over watertown, several thousand police, i would say, have been here going door to door trying to find this suspect. so far without success. we expect the governor, he's just pulled up over here with heavily armed police surrounding him, as well and, in fact, before they set this up, they had dogs come through th